1. Related Technical Fields
Related technical fields include map image display systems, map image display devices, map image display methods, and computer programs for displaying a map image.
2. Related Art
Recently, a navigation device is mounted in many cases in a vehicle to give driving guidance of the vehicle to allow the driver to reach the desired destination easily. A navigation device refers to a device that detects the vehicle's current position using a GPS receiver, acquires map data on the current position from a recording medium, such as a DVD-ROM or an HDD, or via the network, and displays the map image of the area surrounding the current position on a liquid crystal monitor. Such a navigation device draws the background (sea, river, flatland, forest, mountain, etc.) and the road shape as the map image of the area surrounding the current position. In addition, the map image includes traffic announcements, the navigation route, the POI marks indicating facilities, and so on. Recently, a mobile phone, a Personal Digital Assistant (PDA), and a personal computer have the function similar to that of the navigation device described above.
In addition, some of the recent navigation devices, such as that disclosed in Japanese Patent Application Publication No. 2002-72869 (JP 2002-72869 A) (page 5 to 7 and FIG. 4), displays a map image on a display unit three-dimensionally to increase the user's visibility of the map image.